so...spin off, fill new one with diesel, spin on, prime and go? sounds TOO easy.....nothing ever goes that easy for me....ever.
You are correct - sometimes it is not that easy! First off, you mentioned filling the filter with diesel before installing. That is a good idea, except it won't work on the 3116 engine. The filter screws on facing down, so the diesel will pour out.
Now for the potential problems. On my A3, the filter was on so tight that I severely distorted the can getting it loose. I needed an oil filter strap wrench that fit the diameter of the fuel filter. It was so tight I still couldn't break it loose. Then I took a long crescent wrench and put it on the handle of the strap wrench, pointing up. Then I either put a shaft through the hole in the end of the crescent wrench or used a pipe wrench - I can't remember which worked, because I tried both. It then came loose with a loud bang but only after partially twisting the filter can like a pretzel and I was pulling on that wrench with everything I had in me. The other problem I had was that the drain petcock on the bottom of the separator was plugged solid with crud. I needed to rod it out with a piece of welding rod before fuel would flow out. And then for the worst problem. The TM simply says re-start the engine. after installing the filter No problem, right? Wrong! Apparently everyone else has been able to simply restart their engine without bleeding off the air, as the TM suggests. Mine started right up and ran for a few seconds before the air got to it. It took a lot of cranking over a period of time to get mine to restart. I mean a lot of cranking. The TM was of no help, because since it just says to restart the engine, there are no directions on how to bleed the air out.
Changing out the fuel filter prior to recovery is a good idea, but I would highly recommend taking the truck out of the GL lot and off post first to a place you can work on it if you have problems and where you can leave it temporarily if needed without worrying about GL and the removal deadline. As previously mentioned, take along a second new filter in case crud clogs the new one you installed.
During my recovery, I didn't change out the filter prior to my 1,000 mile recovery, although I had a new one with me. The main reason was that my recovery was in January in Wisconsin and it was bitterly cold. The truck ran fine and I reasoned that I could change the filter later if needed. Good luck!